People who are obese may be more susceptible to environmental food cues than their lean counterparts due to differences in brain chemistry that make eating more habitual and less rewarding, according to a National Institutes of Health study published in Molecular Psychiatry External Web Site Policy.
Researchers at the NIH Clinical Center found that, when examining 43 men and women with varying amounts of body fat, obese participants tended to have greater dopamine activity in the habit-forming region of the brain than lean counterparts, and less activity in the region controlling reward. Those differences could potentially make the obese people more drawn to overeat in response to food triggers and simultaneously making food less rewarding to them. A chemical messenger in the brain, dopamine influences reward, motivation and habit formation.
“While we cannot say whether obesity is a cause or an effect of these patterns of dopamine activity, eating based on unconscious habits rather than conscious choices could make it harder to achieve and maintain a healthy weight, especially when appetizing food cues are practically everywhere,” said Kevin D. Hall, Ph.D., lead author and a senior investigator at National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of NIH. “This means that triggers such as the smell of popcorn at a movie theater or a commercial for a favorite food may have a stronger pull for an obese person — and a stronger reaction from their brain chemistry — than for a lean person exposed to the same trigger.”
Study participants followed the same eating, sleeping and activity schedule. Tendency to overeat in response to triggers in the environment was determined from a detailed questionnaire. Positron emission tomography (PET) scans evaluated the sites in the brain where dopamine was able to act.

By Tanya Lewis,
In an experiment that sounds more like science fiction than reality, two humans were able to send greetings to each other using only a digital connection linking their brains.
Using noninvasive means, researchers made brain recordings of a person in India thinking the words "hola" and "ciao," and then decoded and emailed the messages to France, where a machine converted the words into brain stimulation in another person, who perceived the signals as flashes of light. From the sequence of flashes, the French recipient was able to successfully interpret the greetings, according to a new study published today (Sept. 5) in the journal PLOS ONE.
The researchers wanted to know if it is possible for two people to communicate by reading out the brain activity of one person and injecting that activity into a second person.
"Could we develop an experiment that would bypass the talking or typing part of [the] Internet and establish direct brain-to-brain communication between subjects located far away from each other, in India and France?" co-author Dr. Alvaro Pascual-Leone said in a statement. Pascual-Leone is a neurologist at Beth Israel Deaconess Medical Center in Boston, and a professor at Harvard Medical School, in Cambridge, Massachusetts.
To answer that question, Pascual-Leone and his colleagues at Starlab Barcelona, in Spain, and Axilum Robotics, in Strasbourg, France, turned to several widely used brain technologies.
Electroencephalogram, or EEG, recordings are taken by placing a cap of electrodes on a person's scalp, and recording the electrical activity of large regions of the brain's cortex. Previous studies have recorded EEG from a person thinking about an action, such as moving his or her arm, while a computer translates the signal into an output used to move a robotic exoskeleton or drive a wheelchair.